Confocal microwave imaging for breast cancer detection: localization of tumors in three dimensions

TLDR

Microwave imaging detects breast tumors by exploiting dielectric contrast between normal and malignant tissue, using ultra‑wideband pulses from multiple antennas and synthetic focusing of reflected signals. The study demonstrates the feasibility of detecting and localizing sub‑centimeter tumors in 3‑D using numerical models of synthetic cylindrical and planar antenna arrays. Detection relies on coherently summing returns from strongly scattering tumors, with image‑formation algorithms that suppress early‑time skin reflections and late‑time tissue heterogeneity, while varying array size and placement to optimize performance. Both planar and cylindrical configurations successfully detected 6‑mm spherical tumors, yielding comparable performance metrics.

Abstract

The physical basis for breast tumor detection with microwave imaging is the contrast in dielectric properties of normal and malignant breast tissues. Confocal microwave imaging involves illuminating the breast with an ultra-wideband pulse from a number of antenna locations, then synthetically focusing reflections from the breast. The detection of malignant tumors is achieved by the coherent addition of returns from these strongly scattering objects. In this paper, we demonstrate the feasibility of detecting and localizing small (<1 cm) tumors in three dimensions with numerical models of two system configurations involving synthetic cylindrical and planar antenna arrays. Image formation algorithms are developed to enhance tumor responses and reduce early- and late-time clutter. The early-time clutter consists of the incident pulse and reflections from the skin, while the late-time clutter is primarily due to the heterogeneity of breast tissue. Successful detection of 6-mm-diameter spherical tumors is achieved with both planar and cylindrical systems, and similar performance measures are obtained. The influences of the synthetic array size and position relative to the tumor are also explored.